Many existing vendors offer software that creates and displays images, including the display of color or grayscale images that appear to be three dimensional. These images are typically based on data describing a volume of material or human tissue. In the field of medical imaging, devices such as CT, MRI, PET, and Ultrasound can generate data describing a volume of human or animal tissue. It is common for caregivers to display these volumes in a manner such that one or more images appear to be three dimensional using techniques such as volume rendering and surface shading. In addition, such software many enable the user to perform multi-planar reconstructions, maximum intensity pixel displays, or display grayscale or color slabs of various thickness and orientations.
When faced with a display of a three dimensional image, the user may want to rotate the image in any one of three axes or combinations thereof. Often, this rotation is controlled by an input device such as a mouse. For example, depression of a left mouse button combined with movement of the mouse from left to right might control rotation of the image from left to right (rotation about y axis), similar movement of the mouse away from or toward the user might control tilting of the image from toward or away from the perspective of the user (rotation about x axis) and some other sweeping movement of the mouse around the perimeter of the image in a near circular motion might control rotation of the image about the z axis. However, such mouse movements may be ambiguous, so that a user intending to rotate an image in the z axis may accidentally instead cause a rotation in the x axis (possibly in combination with movement in the z and/or y axes). Furthermore, a mouse may control other actions, such as cropping of the image in various planes, so that mouse movements intended to cause rotation may result in inadvertent cropping and other actions.